Within the conventional in vitro fertilization (IVF) process, aiming at obtaining as many embryos as possible is the most common pathway followed, this way increasing chances for success. That is the reason why some embryos usually remain unused at the end of the fertility treatment.
In the United States in particular, we can choose which will be the fate of our leftover embryos out of the four possible options available:
- Cryopreservation: this one is about keeping the embryos frozen in order to be able to use them in future embryo transfers, either because of implantation failure in the previous cycle or because you wish to have a second child.
- Embryo donation for reproductive purposes, i.e. donating them to other patients who are unable to conceive using their own gametes.
- Embryo donation for fertility research purposes
- Destroying them
Embracing donated embryos
Donor egg recipients should be aware of the risks this technique entails, since there is the possibility that the required safety screening has not been performed. Such procedure is done according to tissue guidances given by the FDA (Food and Drug Administration) in relation to tissue donation (i.e. eggs, sperm, or embryos) and are necessary because it should be taken into account that these embryos were not meant to be donated but used by the ones they were created from.
Even though achieving motherhood/fatherhood via embryo donation is allowed to every individual person or couple across the USA, this fertility treatment is particularly indicated in the following cases:
- Infertile, single women (due to poor egg quality or no egg production)
- Couples where both members suffer from infertility, which prevents them from using their own gametes
- Recurrent implantation failure
- Genetic abnormalities in eggs and/or sperm
US regulations on this matter establish no specific age limit for egg donor recipients. However, from agn 45 onwards, recipients are recommended to undergo a series of screening tests as well as visiting a physician who specializes in high-risk pregnancy.
Embryo donation success rates
Success rates of embryo donation, also known as embryo adoption, depend to a large extent on both egg and sperm quality from which the embryos were created.
In this sense, factors such as how old embryo donors were, what led them to the need of assisted reproductive technology, etc. should be taken into account.
There is also the possibility that donor embryos have been created from donor gametes, that is to say, the embryo donors used an egg and/or sperm donor, in which case donor embryo quality will improve.
Also noteworthy is the fact that, since donor embryos have been created in previous IVF cycles, they will have always gone through an embryo freezing process prior to being adopted. For this reason, they may have experienced a slight loss of quality due to the thawing process. Nevertheless, thanks to freezing systems used generally nowadays, called vitrification, the loss of quality is minimal and survival rates are, conversely, high.